Atherosclerosis is a progressive disease of the vascular system whereby atheroma is deposited on the inner walls of blood vessels. Atherosclerosis is a complex degenerative condition resulting in the build-up of cholesterol, calcium, and other obstructive materials, known as plaque, on the walls of the arteries. The accumulation of plaque narrows the interior lumen of arteries, thereby reducing blood flow.
Plaque occurs in the arteries in several different forms and may be located in many different anatomies throughout the arterial system. Plaque varies in composition, with portions that are hard and brittle, referred to as calcified plaque, and other portions that are fatty or fibrous. Over time atheromatous deposits can become large enough to reduce or occlude blood flow through the vessels, leading to symptoms of low blood flow, such as claudication (pain in the legs on walking or at rest), skin ulcer, critical limb ischemia, and other symptoms. To treat this disease and improve or resolve these symptoms it is desirable to restore or improve blood flow through the vessel.
Various means are used to restore or improve blood flow through atheromatous vessels. The atheroma deposits can be displaced by diametrically expanding the vessel by inflating balloons, expanding stents, and other methods. The deposits can be fragmented using lasers and other methods. Atherectomy catheters can be used to remove atheromatous deposits from the blood vessel.
Many types of atherectomy catheter devices have been proposed, including catheters with rotating burrs, lasers to photodissolve tissue, and cutter-balloon catheters. The various catheter embodiments described herein incorporate improvements with respect to the structure of the catheters and methods of use and manufacture.